Many electronic devices require hinge mounted covers. These hinges usually require friction or detents to control the positioning of the cover. In some instances, both friction and one or two detents are considered desirable. Smaller hinges are required as electronic devices have, themselves, become smaller. Most friction hinges of the prior art produce constant friction as function of angle. A few friction hinges have been disclosed which permit the torque to vary with angle, although these have usually been too large in size for small modern electronic equipment. A further troublesome characteristic of prior art hinges is that the friction and/or detenting forces are produced by components within the hinge that are not symmetrically disposed about the hinge axis. The result of this asymmetry is that forces are produced in the bearings during rotation of the hinge. These forces are undesirable because they are an extra source of friction that is hard to control. Also, this bearing friction results in bearing deterioration, wear, and lost motion.
The present invention provides a small, cylindrical hinge, or pivoting pin, which can be configured to produce various profiles of torque versus angle. The desired profile of torque versus angle is achieved by the shapes of the hinge shaft and the spring plates of the hinge. Detents at one or more angular positions can be achieved, with or without frictional damping torque at other angles. The friction of our hinge is produced symmetrically about the hinge axis, eliminating the problems associated with asymmetric construction.